Impairments in cognitive ability and attention are pervasive and potentially debilitating components of many disorders, conditions, injuries and diseases, including mild cognitive impairment (MCI) in persons with pre-dementia, dementia, dementia with Lewy bodies, Alzheimer's Disease, traumatic brain injury, Attention Deficit/Hyperactivity Disorder (ADHD), and cognitive/attentional declines associated with chronic diseases such as diabetes, cardiovascular disease, and HIV infection [1, 2, 3, 4, 5, 6, 7, 8]. Most of these disorders are assumed to be pathology-based and therefore amenable to intervention, especially if diagnosed early.
ADHD is one of multiple disorders associated with impairments in attention. Although this document may particularly identify attentional disorders associated with ADHD, the various embodiments of the present invention shall be applied to any disorder with associated attentional impairments. With respect to dementia, recent research and a review of the literature conclude that the frequency of post stroke dementia and cognitive decline varied sharply when different systems of diagnostic classification and methods were used [10]. Furthermore, recent findings support the need for validation not only of the criteria, but also the need for validated measures to diagnosis dementia and cognitive impairment post stroke [10, 11, 12], and Alzheimer's disease [13]. In addition, cognitive abnormalities commonly occur in patients with HIV infection [14]. Among otherwise healthy HIV-positive patients, cognitive deficits are thought to be infrequent [15], but some investigators suggest that more sensitive measures may be needed to detect the mild cognitive decline during the asymptomatic stage [16].
The hallmarks of ADHD are hyperactivity, impulsivity, and an inability to sustain attention. The DSM-IV distinguishes three types: predominantly inattentive type, predominantly hyperactive-impulsive type, and combined type. In addition to the core clinical symptoms of ADHD, high levels of co-morbidity have been found with learning, oppositional defiant, conduct, mood, and anxiety disorders. Furthermore, it is estimated that the majority of children diagnosed with ADHD exhibit significant behavioral problems during adolescence and manifest continuing functional deficits and psychopathology into adulthood. One real-life consequence of ADHD is a five-fold increase in automobile crashes [21].
Early diagnosis and treatment of Alzheimer's disease, dementia, and additional progressive disorders associated with attentional impairment is especially important because patients with early stages of dementia may show reversal of their cognitive deficits and neurochemistry abnormalities after treatment [8].
There are numerous disorders and diseases associated with impairment of attention and cognitive functioning, however, the diagnosis and quantification of impairment of attention in any disease or disorder is typically difficult. Some examples include: attentional impairments associated with ADHD, HIV infection, Alzheimer's Disease, cardiovascular disease, diabetes, and dementia.
With respect to ADHD, the DSM-IV [17] states “The essential features of ADHD are a persistent pattern of inattention and/or hyperactivity-impulsivity that is more frequent and severe than is typically observed in individuals in a comparable level of development.” Evidence of six of nine inattentive behaviors and/or six of nine hyperactive-impulsive behaviors must have been present before age seven, and must clearly interfere with social, academic and/or occupational functioning. Consequently, the diagnosis of ADHD is highly dependent on a retrospective report of a patient's past behavior and subjective judgments on degree of relative impairment. Due to the subjective nature of assessment, precision in diagnosis has been elusive. ADHD is complex and influences all aspects of a person's life. It can co-exist with and/or mimic a variety of health, emotional, learning, cognitive, and language problems. An appropriate, comprehensive evaluation for ADHD includes a medical, educational, and behavioral history, evidence of normal vision and hearing, recognition of systemic illness, and a developmental survey. The diagnosis of ADHD should never be made based exclusively on rating scales, questionnaires, or tests [18].
Diagnosing ADHD presents a challenge to traditional assessment paradigms because there is no single assessment tool or medical test that definitively establishes its presence (See Hinshaw, S. P. (1994), “Attention Deficits and Hyperactivity in Children,” Thousand Oaks, Calif., Sage, and Penberthy, J. K., Cox, Breton, M., Robeva, R., Kalbfleisch, M. L., Loboschefski T., Kovatchev, B. (2005), “Calibration of ADHD Assessments Across Studies: A Meta-Analysis Tool,” Applied Psychophysiology and Biofeedback, Vol. 30, No. 1, pp 31-51, of which are hereby incorporated by reference herein in their entirety). Instead, there are multiple tests of varying design, each of which has its own administration, scoring system, and diagnostic criteria. Unfortunately, none of these individual assessments has proven to be 100 percent accurate in diagnosing ADHD. This is to be expected, however, since ADHD is considered to be a physiologically-based disorder with a multi-factorial etiology that includes neurobiology as an important factor, and would not be easily classified by only one assessment tool. In fact, the reliability of the ADHD diagnosis based on one method or test alone is quite low, and lower still when chance agreement is considered. For example, previous research has found 78 percent agreement between a structured interview and a discharge diagnosis of ADHD (See Welner, Z., Reich, W., Herjanic, B., Jung, K. G. (1987), “Reliability, Validity, and Parent-child Agreement Studies of the Diagnostic Interview for Children and Adolescents (DICA),” Journal of the American Academy of Child and Adolescent Psychiatry, 26(5), 649-653, of which is hereby incorporated by reference herein in it's entirety) and 70 to 80 percent accuracy (with considerable variation depending on age range) of laboratory measures of attention in correctly predicting an ADHD diagnosis (See Fischer, M., Newby, R. F., Gordon, M. (1995), “Who are the False Negatives on Continuous Performance Tests?”, Journal of Clinical Child Psychology, 24, 427-433, of which is hereby incorporated by reference herein in it's entirety).
Of even greater importance, there is currently no uniform methodology for calibrating or standardizing the multiple disparate ADHD assessment tools currently available for clinicians and researchers.
What is needed is a methodology for producing a single result from disparate assessments and tests in order to not only provide a more accurate diagnosis, but to also enable the combination of multiple studies of ADHD assessments, thus increasing the sample size and providing more power, generalizability, and possibilities for cross-sectional comparisons. Such a procedure would be especially useful in situations such as diagnosing ADHD, when there is no single conclusive assessment but rather a number of imperfect tests that marginally address the outcome of interest, and where researchers may have multiple related tests performed on a single subject which they wish to combine into a more comprehensive assessment of the individual.